1. Field of the Invention
The present invention relates to an interpolation image generating method of generating an interpolation image between a first reference image and a second reference image and an apparatus therefor.
2. Description of the Related Art
In recent years, opportunities displaying a video image on various displays such as a cathode ray-tube (CRT), a liquid crystal display (LCD), and an organic electroluminescence display (EL Display) have been increasing. These displays are divided into a hold type display and an impulse type display by a displaying method. In the hold type display such as LCD and EL display, a certain frame of a displayed video image is held during one frame period. Therefore, even if a viewer watches a moving object while he or she follows the moving object smoothly, because the moving object moves discontinuously every frame period, the moving object is recognized as a blurred image by the viewer due to deviation between a smooth movement of the eyeshot of the viewer and a discontinuous movement of the displayed moving object. Generally this is called moving image degradation due to a hold effect.
The video image has various frame rates depending on its uses. Also, a display has various frame rates, so that the frame rate of the video image must be converted according to a display to display the video image. For example, the movie has 24 frames per second (24 fps). A pull down conversion is used for displaying the movie on a display device having a refresh rate of 60 Hz. This simply converts a frame rate by displaying the same frame two or three times. However, in the above method, since the number of frames of the video image is insufficient, the movement of the object becomes discontinuity unnaturally, resulting in jerky motion.
It is necessary for solving the above problem to increase the number of frames by producing a new interpolation frame according to movement of the moving image. As a method of generating an interpolation frame, there are a method of deriving a motion vector of a block by the block matching that is used by, for example, MPEG (Motion Picture Experts Group), and generating an interpolation frame using it, and a method of doing a motion vector search using a block and thereafter searching a peripheral of a motion vector of a block reference with a pixel level so as to be able to correspond to smaller movement (referring to Japanese Patent Laid-Open No. 11-112940, for example).
As discussed above, a method of generating an interpolation frame using a motion vector between two frames cannot obtain a correct motion vector in a hidden surface (occlusion) region.
An object of the present invention is to provide an interpolation image generation method of generating a correct interpolation image on an occlusion region.